This invention relates generally to landing gear for semitrailers and more particularly to thrust bearings and collars used in landing gear.
Semitrailers typically having landing gear which may be extended to support the trailer when the trailer is uncoupled from the tractor. Conventional landing gear includes a body attached to the vehicle and a telescoping leg received in the body. A screw shaft rotatably connected to the body has external threads which engage internal threads in a nut attached to the leg. The screw shaft is rotated in the one direction to move the leg downward relative to the body into an extended position in which the landing gear engages the ground to support the trailer. The screw shaft is rotated in an opposite direction to move the leg upward relative to the body into a retracted position in which the landing gear clears the ground for transporting the trailer with the tractor.
Among the numerous components of conventional landing gear assembly are a thrust bearing and a collar. The thrust bearing is mounted on the screw shaft below a bearing block to journal the shaft for rotation on its axis. The collar, mounted on the shaft below the bearing, distributes loads from the shaft to the bearing. During initial assembly, the assembler fixes the collar on a shoulder of the screw shaft or, alternatively, welds the collar to the shaft, which eliminates the need for the shaft shoulder. Next, the thrust bearing is placed on the shaft such that the lower race is adjacent the collar. As a result, two separate components, a thrust bearing and a collar, are required to be positioned during the assembly of a conventional landing gear.
It is typically desirable for manufacturers of assembled goods to minimize the number of components needed for final assemblage of their product. Such minimization usually results in reduced costs by cutting labor costs, handling costs, processing costs and transportation costs. Labor costs are reduced because the assembler can assemble the product with fewer steps and therefore potentially less time. Since assemblers are commonly paid on an hourly basis, less time necessary for the assemblage of a unit results directly in a reduction of labor costs because more units can be produced during a given time period.
In addition, the transportation and handling costs are reduced. Typically, parts used in the assembling processes are manufactured at a facility or facilities separate from that in which assembly occurs. Furthermore, it is not uncommon that the various components are manufactured by one or more vendors. Accordingly, each component used in the assembling of a product needs to be shipped to the assembling facility, unloaded, stored, inventoried and transported from storage to the assembling station when needed. In addition, costs are incurred for each component by placing orders, processing accounts payables for delivered goods, maintaining quality assurance and managing the receiving department. Accordingly, if the number of parts that need to be inventoried, ordered, shipped, unloaded, stored and invoiced are reduced, the labor and associated costs for each of these activities are also reduced.